1.3 - Membrane Proteins

Question 1

types of membrane protein

Answer 1

integral and peripheral proteins

Question 2

integral proteins

Answer 2

proteins which interact with the hydrophobic tails of the plasma membranes phospholipid bilayer

Question 3

peripheral proteins

Answer 3

proteins attached to the phospholipid hydrophilic head in the plasma membrane

Question 4

fluid mosaic model

Answer 4

shows the arrangement and structure of the plasma membrane

Question 5

transmembrane protains

Answer 5

proteins which span the entire width of the plasma membrane - some integral proteins are transmembrane

Question 6

how are integral proteins held in the phospholipid bilayer

Answer 6

by hydrophobic interaction between the integral proteins R groups and the hydrophobic tail of the phospholipid

Question 7

how are peripheral proteins held on the surface of the bilayer

Answer 7

by ionic and hydrogen bonding interactions with the hydrophilic head of the phospholipid bilayer

Question 8

interaction between integral and peripheral proteins

Answer 8

they interact on the surface exterior of the phospholipid bilayer

Question 9

phospholipid bilayer characteristics

Answer 9

the head is hydrophobic
the tail is hydrophilic

Question 10

rule for molecules passing through the bilayer

Answer 10

small molecules (carbon dioxide and oxygen) can pass through the bilayer
uncharged polar molecules and ions cannot pass through the bilayer due to ionic head.

Question 11

facilitated diffusion definition

Answer 11

the passive transport of a substance across a membrane through specific transmembrane proteins

Question 12

how do specialised plasma membrane functions take place

Answer 12

different cell types will have unique transporter and channel proteins

Question 13

channel proteins

Answer 13

highly selective multi subunit proteins with subunits arranged to form water filled pores that extend across the membrane

Question 14

types of channel proteins

Answer 14

ligand gates and voltage gated

Question 15

ligand gated channel proteins

Answer 15

channel proteins controlled by the binding of a signal molecule which allows for a conformational change, which will open the channel an allow specific molecules down the concentration gradient into the cell

Question 16

voltage gated channel proteins

Answer 16

channel proteins controlled by changes in ion concentration, which undergo a conformational change when the membrane potential changes

Question 17

transporter proteins

Answer 17

proteins which bind to a specific substance, which will cause the protein to undergo a conformational change and transfer the molecule across the membrane

Question 18

specific feature of transporter proteins

Answer 18

they will alternate between two conformations so that the binding site is on opposite sides of the plasma membrane

Question 19

pump proteins

Answer 19

transmembrane proteins which actively transport molecules across the membrane against the concentration gradient

Question 20

active transport

Answer 20

the movement of molecules against a concentration gradient using protein pumps and requiring energy

Question 21

ATPases

Answer 21

a type of protein pump which directly hydrolyses ATP to produce the energy needed for active transport

Question 22

electrochemical gradient definition

Answer 22

the concentration gradient and the electrochemical potential difference

Question 23

electrical potential difference

Answer 23

also called membrane potential - the difference in electrical charge of the inside and outside of a cell

Question 24

concentration gradient

Answer 24

how molecules moves from high to low concentratio

Question 25

normal potential difference in extra cellular fluid

Answer 25

-70mV

Question 26

sodium concentration inside cell

Answer 26

low

Question 27

sodium concentration outside of cell

Answer 27

high

Question 28

potassium concentration inside cell

Answer 28

high

Question 29

potassium concentration outside cell

Answer 29

low

Question 30

sodium potassium pump process

Answer 30

• 3 sodium ions will bind to the inside of the pump due to high affinity
• ATP is hydrolysed breaking down into ADP and Pi, Pi phosphorylates the sodium potassium ATPase
• conformational change will occur allowing for sodium to be released outside the cell
• 2 potassium will then bind to sites outside the cell due to high affinity
• The sodium potassium ATPase will then be dephosphorylated
• this will allow conformational change to occur which will allow 2 potassium ions to be pumped into the cell

Question 31

reason for sodium potassium pump

Answer 31

to maintain sodium and potassium ion gradients

Question 32

how does sodium enter the cell

Answer 32

by facilitated diffusion by voltage gated channel proteins

Question 33

how does potassium leave the cell

Answer 33

by facilitated diffusion by voltage gated channel proteins

Question 34

type of transport for sodium potassium pump

Answer 34

active transport

Question 35

what percentage of energy is used by sodium potassium ion pump

Answer 35

25% basal metabolic rate (High)

Question 36

uses of sodium potassium pump

Answer 36

small intestine epithelial cells, neurone firing

Question 37

number of sodium out of cells in sodium potassium pump

Answer 37

3 ions

Question 38

number of potassium into cells in sodium potassium pump

Answer 38

2 ions

Question 39

sodium potassium pump process in intestinal epithelial cells

Answer 39

low concentration of sodium in intracellular fluid is pumped into high sodium concentration extra cellular fluid.
the sodium then undergoes facilitated diffusion back inside the cell along with the facilitated diffusion back inside the cell along with the transport of a glucose molecule

Question 40

symport definition

Answer 40

where two molecules are transported across the membrane by the same transporter protein

Question 41

symporter definition

Answer 41

a transmembrane protein which transports two different molecules across the plasma membrane at the same time